Diagnostic and statistical approach to the validation of Doppler radar rainfall around Chennai during 2006-2010

Abstract

Rainfall data obtained from the precipitation accumulation product of the Doppler Weather Radar at Chennai has been compared and validated with the rainfall recorded at 16 stations located within 100 km range of the radar. Statistical parameters, like correlation, mean error and mean absolute error have been calculated. When rainfall is indicated by both radar and observatory, a high degree of correlation, at 0.98, between the conditional means of radar and observatory rainfall in various ranges is observed along with consistency in underestimation of rain by radar. A regression equation has been constructed to correct the rainfall estimates from radar. Physics and radar engineering aspects, which contribute towards limitations in rainfall estimation, have been discussed.